Model : #4 N4 Spark Glow Plug The tungsten filament of N4 is more bolder than the N3,more durable. RC Engine Glow Plugs & Spark Plugs - RC Engine Glow Plugs & Spark Plugs / RC Eng Aazon.co: CrazyHobby N4#4 NO.4 Glow Plug 70117 ediu Hot Spark Nitro... Longer lasting element For 4c Engines For 5% - 40% Nitro Fuels Improves Idle and transition; Hex Size: 8mm Quantity:3Pcs/5Pcs(Optional) Package includes: 5Pack No., 4 Hot Glow Plug Compatible with SHOCKWAVE, TSUNAMI, VOLCANO STX, TORNADO S30, VOLCANO S30, AFTERSHOCK 21, HURRICANE XL, AFTERSHOCK 3., 0, AFTERSHOCK 3., 5, BACKDRAFT 3., 5, CALDERA 3., 0, EARTHQUAKE 3., 0, EARTHQUAKE 3., 5, HURRICANE XP, LANDSLIDE 21, LANDSLIDE LT, MAELSTROM LT, MONSOON XP, SANDSTORM 21, SANDSTORM LT, TWISTER LT, TYPHOON XP, REACTOR RS 3., 3, VOLCANO MX, VOLCANO SV, VOLCANO T2, VORTEX SS, TORNADO BB and more., ., ., Medium for club racing and sport use. Item: Hot Glow Candle N4 No.4 Material: steel; height: 17.2 mm; Improves idle and transition, longer lasting element. For 4c engines 5% - 40% nitro fuels Improves Idle and transition;Hex Size: 8mm Medium Hot Spark Plug ShareGoo RC Glow Plug #4 N4 Medium Hot Spark Nitro Engine Nitro Engine Spark Plug Quantity:3Pcs/5Pcs(Optional)